INTRODUCTION. xxxui 



plemented by lines of soundings and dredgings taken from low-water mark 

 to the depths at which oceanic slopes are met. 



The data thus obtained would give us the pitch of the slope of the strata 

 underlying a bai'rier and a fringing reef, and of its continuation beyond 

 the outer edge of the barrier reef. For an atoll the bore would indicate 

 the width of the talus, the original dimensions of the summits upon which 

 the recent reef rock material was deposited, and the extent of lateral 

 growth, both seaward and lagoonward. This would give a degree of pre- 

 cision now wanting in the observations I have recorded. 



ALEXANDER AGASSIZ. 

 Newport, Rhode Island, October 20, 1902. 



